Chemical mechanical polishing composition

Abstract

The invention discloses a chemical mechanical polishing composition. The chemical mechanical polishing composition is used for achieving SiN / TEOS selection ratios at different polishing rates. The invention also specifically discloses that a preferred trivalent transition metal ion compound ferric nitrate nonahydrate is added into the cerium oxide polishing solution, the polishing rate of SiN can be effectively improved under different pressures (1.5 psi, 2.0 psi and 3.0 psi), the concentration range (1-100ppm) and the pH range (4.0-9.0), and the cerium oxide polishing solution has a relatively wide operation window. And meanwhile, different SiN / TEOS selection ratios can be realized by adjusting the adding amount of the ferric nitrate nonahydrate (III). In addition, under the pressure of 3.0 psi, the lanthanum nitrate hexahydrate (III) and the cerium nitrate hexahydrate (III) can also effectively improve the polishing rate of SiN within the concentration range (20-100 ppm) and the pH range (4.0-9.0).

Description

Technical Field

[0001] The invention relates to a cerium oxide chemical mechanical polishing liquid, and more specifically, to a chemical mechanical polishing composition which uses trivalent transition metal ions as additives to effectively achieve SiN / TEOS selectivity ratios with different polishing rates. Background Art

[0002] In the manufacturing process of semiconductor devices, chemical mechanical polishing (CMP) has become the most effective and mature planarization technology. In chemical mechanical polishing solutions based on different abrasives, cerium oxide particles can still provide a higher polishing rate at a lower content, and can also obtain a higher selectivity, which has important application value in CMP. Generally, most chemical mechanical polishing solutions strive to reduce the removal rate of silicon nitride and obtain relatively high removal rates for other materials. For example, in the widely concerned shallow trench isolation (STI) process, silicon nitride (SiN) is used as the termination layer, and the chemical mechanical polishing solution used requires a higher silicon dioxide (TEOS) removal rate.

[0003] However, with the advancement of semiconductor etching technology, the oxide line width gradually becomes smaller, and it is expected that the chemical mechanical polishing liquid used has the advantage of polishing silicon nitride over polishing oxide, that is, it has the opposite selectivity requirement from the traditional STI, which can minimize the defects in the oxide line formed on the substrate surface. Therefore, it is a problem to be solved to find a polishing liquid that can improve the polishing rate of silicon nitride. The present invention can effectively improve the polishing rate of SiN by adding trivalent transition metal ions to the cerium oxide polishing liquid. At the same time, by adjusting the content of the preferred trivalent transition metal ions, different SiN / TEOS selectivity ratios can be achieved. Summary of the invention

[0004] The invention discloses a chemical mechanical polishing composition, comprising: water; cerium oxide abrasive particles; and a trivalent transition metal ion compound.

[0005] Furthermore, in the chemical mechanical polishing composition, the trivalent transition metal ion is iron (III), lanthanum (III) or cerium (III).

[0006] Furthermore, the trivalent transition metal ion compound is iron (III) nitrate nonahydrate, lanthanum (III) nitrate hexahydrate or cerium (III) nitrate hexahydrate.

[0007] Furthermore, the concentration range of the trivalent transition metal ion compound is 1-100 ppm.

[0008] Furthermore, the mass percentage content of the cerium oxide abrasive particles ranges from 0.02% to 0.4%.

[0009] Furthermore, the pH value of the polishing composition ranges from 4.0 to 9.0.

[0010] Furthermore, the polishing composition further comprises a pH adjuster, and the pH adjuster is selected from an inorganic acid or an inorganic base, preferably HNO3 or KOH.

[0011] The present invention adds a preferred trivalent transition metal ion compound iron (III) nitrate nonahydrate to the cerium oxide polishing liquid, and can effectively improve the polishing rate of SiN under different pressures (1.5psi, 2.0psi and 3.0psi), concentration ranges (1-100ppm) and pH ranges (4.0-9.0), with a wide operating window. At the same time, by adjusting the addition amount of iron (III) nitrate nonahydrate, different SiN / TEOS selectivity ratios can be achieved. In addition, under a pressure of 3.0psi, lanthanum (III) nitrate hexahydrate and cerium (III) nitrate hexahydrate can also effectively improve the polishing rate of SiN within a concentration range (20-100ppm) and a pH range (4.0-9.0). Specific embodiments

[0012] Embodiment 1

[0013] The raw materials used in this example are all commercially available. According to the ratio of each component in Table 1, each component was dissolved in deionized water, and the mass percentage was supplemented with deionized water to 100%. 3 or KOH) to adjust the pH to 4.5 to obtain the polishing solutions of Comparative Examples 1A-1C and Examples 1D-1F of the present invention.

[0014] Table 1 Components and contents of the polishing liquids of the comparative examples and the examples

[0015]

[0016] In order to further measure the polishing performance of the polishing solution in each embodiment and comparative example, the polishing rate of the polishing solution on TEOS wafer and SiN wafer was measured at different polishing pressures of 1.5psi, 2.0psi or 3.0psi, respectively. The results are shown in Table 2.

[0017] Polishing conditions: the polishing machine is Ebara F-REX-300X, the polishing pad is IK4350, the platen and head speeds are 93 rpm and 87 rpm respectively, the polishing pressure is 1.5 psi, 2.0 psi or 3.0 psi, the polishing liquid flow rate is 300 mL / min, and the polishing time is 60 s.

[0018] Polishing step: The TEOS and SiN blank wafers were polished using the polishing liquid prepared above using the polishing instrument and polishing conditions described above. The film thickness measuring instrument was the NanoSpec film thickness measuring system (NanoSpec6100-300, Shanghai Nanospec Technology Corporation). The principle is to measure 49 points at equal intervals on the diameter line starting from 3 mm from the edge of the wafer, and test their polishing rates respectively. The polishing rate of each polishing liquid is the average of the polishing rates at the 49 points.

[0019] Table 2 Polishing rate of comparative example and example polishing liquid under different polishing pressures

[0020]

[0021] From the polishing results of Comparative Examples 1A and 1C, it can be seen that the addition of aluminum (III) nitrate nonahydrate significantly inhibits the polishing rate of SiN. The polishing results of Comparative Example 1A and Examples 1D and 1E show that under a polishing pressure of 3.0 psi, the addition of lanthanum (III) nitrate hexahydrate or iron (III) nitrate nonahydrate can both increase the polishing rate of SiN. However, under low polishing pressure (1.5 psi or 2.0 psi), the addition of lanthanum (III) nitrate hexahydrate reduces the polishing rate of SiN, while the addition of iron (III) nitrate nonahydrate can still significantly increase the polishing rate of SiN, which can be increased by more than twice.

[0022] From the polishing results of Comparative Example 1B and Example 1F, it can be seen that under a polishing pressure of 3.0 psi, cerium (III) nitrate hexahydrate can also increase the polishing rate of SiN by more than two times, but under low pressure (1.5 psi or 2.0 psi), cerium (III) nitrate hexahydrate has a significant inhibitory effect on the polishing rate of SiN. In summary, in the cerium oxide polishing liquid, adding trivalent transition metal ions can increase the polishing rate of SiN under a certain pressure. Preferably, compared with lanthanum (III) or cerium (III), iron (III) nitrate nonahydrate in the embodiment has a wider polishing pressure operation window, and can significantly promote the improvement of SiN polishing rate at 1.5 psi, 2.0 psi and 3.0 psi.

[0023] Embodiment 2

[0024] According to the ratio of each component in Table 3, each component was dissolved in deionized water, and the mass percentage was supplemented to 100% with deionized water. 3Or KOH to adjust the pH to 4.5, to obtain the polishing solution of Comparative Example 2A and Examples 2B-2H. The polishing solutions of Comparative Example 2A and Examples 2B-2H prepared above were used for chemical mechanical polishing of TEOS and SiN blank wafers, respectively, and the polishing effects were compared. The results are shown in Table 3.

[0025] The polishing conditions are as follows: the polishing machine is Ebara F-REX-300X, the polishing pad is IK4350, the platen and head speeds are 93 rpm and 87 rpm respectively, the polishing pressure is 2.0 psi, the polishing liquid flow rate is 300 mL / min, and the polishing time is 60 s. The film thickness measuring instrument is the NanoSpec film thickness measuring system.

[0026] Table 3 Effect of adding different amounts of iron (III) nitrate nonahydrate on polishing effect

[0027]

[0028] Table 3 shows the effect of adding different amounts of iron (III) nitrate nonahydrate on the polishing effect of cerium oxide polishing liquid. It can be seen that even adding only a trace amount (1ppm, 5ppm) of iron (III) nitrate nonahydrate can increase the polishing rate of SiN. As the content of iron (III) nitrate nonahydrate increases, the SiN rate gradually increases, and the optimal concentration is 50ppm. When the concentration of iron (III) nitrate nonahydrate increases to 100ppm, the SiN polishing rate of Example 2H is still significantly higher than that of Comparative Example 2A, indicating that iron (III) nitrate nonahydrate has a wider concentration range. Compared with Comparative Example 2A, the TEOS polishing rate of Example 2H is significantly suppressed, so the SiN / TEOS selectivity is significantly improved. By adjusting the amount of iron (III) nitrate nonahydrate added, different SiN / TEOS selectivities can be achieved.

[0029] Table 4 shows the effect of adding different amounts of cerium (III) nitrate hexahydrate or lanthanum (III) nitrate hexahydrate on the polishing effect of cerium oxide polishing solution. According to the ratio of each component, each component was dissolved in deionized water, and the mass percentage was supplemented with deionized water to 100%, and HNO 3 Or KOH is used to adjust the pH to 4.5 to obtain the polishing liquids of the comparative example and the example. The polishing liquids prepared above are used for chemical mechanical polishing of TEOS and SiN blank wafers, respectively, and the polishing effects are compared. The results are shown in Table 4.

[0030] The polishing conditions are as follows: the polishing machine is Mirra, the polishing pad is IC1000, the platen and head speeds are 93 rpm and 87 rpm respectively, the polishing pressure is 3.0 psi, the polishing liquid flow rate is 150 mL / min, and the polishing time is 60 s. The film thickness measuring instrument is the NanoSpec film thickness measuring system.

[0031] Table 4 Effect of adding different amounts of cerium (III) nitrate hexahydrate or lanthanum (III) nitrate hexahydrate on polishing effect

[0032]

[0033] It can be seen from Table 4 that when the content of cerium (III) nitrate hexahydrate gradually increases from 20ppm to 80ppm, the polishing rate of SiN gradually increases. When the concentration of cerium (III) nitrate hexahydrate increases to 100ppm, the polishing rate of SiN in Example 3E decreases compared to Example 3D, but is still higher than that in Comparative Example 3A. When the content is further increased to 300ppm, the polishing rate of SiN in Example 3F decreases significantly compared to Comparative Example 3A. When lanthanum (III) nitrate hexahydrate is added, the polishing rate of SiN gradually increases as its content increases from 20ppm to 100ppm. When its content is further increased to 200ppm, the polishing rate of SiN decreases significantly compared to Comparative Example 3G. This shows that under a polishing pressure of 3.0psi, cerium (III) nitrate hexahydrate and lanthanum (III) nitrate hexahydrate can effectively improve the polishing rate of SiN in the concentration range of 20-100ppm.

[0034] Embodiment 3

[0035] According to the ratio of each component in Table 5 and Table 6, each component was dissolved in deionized water, and the mass percentage was supplemented to 100% with deionized water. 3 Or KOH to adjust different pH values ​​to obtain the polishing liquids of the comparative example and the example. The polishing liquids prepared above were used for chemical mechanical polishing of TEOS and SiN blank wafers, and the polishing effects were compared. The results are shown in Table 4.

[0036] The polishing conditions are as follows: the polishing machine is Mirra, the polishing pad is IC1000, the platen and head speeds are 93 rpm and 87 rpm respectively, the polishing pressure is 2.0 psi or 3.0 psi, the polishing liquid flow rate is 150 mL / min, and the polishing time is 60 s. The film thickness measuring instrument is the NanoSpec film thickness measuring system.

[0037] Table 5 Effect of adding iron (III) nitrate nonahydrate on polishing effect under different pH conditions

[0038]

[0039] Table 5 shows the effect of adding 50ppm iron (III) nitrate nonahydrate on the polishing effect of cerium oxide polishing solution under different pH conditions. It can be seen that the addition of iron (III) nitrate nonahydrate in the pH range of 4.0-9.0 in the polishing solution can effectively increase the polishing rate of SiN. The polishing results of Comparative Examples 4A and 4B show that at pH = 3.5, the polishing rate of SiN will be suppressed regardless of whether iron (III) nitrate nonahydrate is added. When the pH is adjusted to 4.0-6.5, the addition of iron (III) nitrate nonahydrate can not only increase the polishing rate of SiN, but also significantly reduce the polishing rate of TEOS. When the pH is further adjusted to alkaline (9.0), the addition of iron (III) nitrate nonahydrate can still significantly increase the polishing rate of SiN, but has little effect on the polishing rate of TEOS.

[0040] Table 6 Effect of adding cerium (III) nitrate hexahydrate or lanthanum (III) nitrate hexahydrate on polishing effect under different pH conditions

[0041]

[0042] Table 6 shows the effect of adding cerium (III) nitrate hexahydrate or lanthanum (III) nitrate hexahydrate on the polishing effect of cerium oxide polishing solution under different pH conditions. Similarly, at pH = 3.5, the polishing rate of SiN will be inhibited. However, adding cerium (III) nitrate hexahydrate or lanthanum (III) nitrate hexahydrate in the polishing solution pH range of 4.0-9.0 can improve the polishing rate of SiN to a certain extent.

[0043] In summary, the present invention adds iron (III) nitrate nonahydrate to the cerium oxide polishing liquid, which can effectively improve the polishing rate of SiN in different pressures (1.5psi, 2.0psi and 3.0psi), concentration ranges (1-100ppm) and pH ranges (4.0-9.0), and has a wide operating window. At the same time, by adjusting the amount of iron (III) nitrate nonahydrate added, different SiN / TEOS selectivity ratios can be achieved. In addition, under a pressure of 3.0psi, lanthanum (III) nitrate hexahydrate and cerium (III) nitrate hexahydrate can also effectively improve the polishing rate of SiN in the concentration range (20-100ppm) and pH range (4.0-9.0).

[0044] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing composition comprising: water; cerium oxide abrasive particles; a trivalent transition metal ion compound.

2. The chemical mechanical polishing composition according to claim 1, It is characterized in that The trivalent transition metal ion is iron (III), lanthanum (III) or cerium (III).

3. The chemical mechanical polishing composition according to claim 1, It is characterized in that The trivalent transition metal ion compound is iron (III) nitrate nonahydrate, lanthanum (III) nitrate hexahydrate or cerium (III) nitrate hexahydrate.

4. The chemical mechanical polishing composition according to claim 1, It is characterized in that The concentration range of the trivalent transition metal ion compound is 1-100 ppm.

5. The chemical mechanical polishing composition according to claim 1, It is characterized in that The mass percentage content of the cerium oxide abrasive particles ranges from 0.02% to 0.4%.

6. The chemical mechanical polishing composition according to claim 1, It is characterized in that The pH value of the polishing composition ranges from 4.0 to 9.

0.

7. The chemical mechanical polishing composition according to claim 1, It is characterized in that The polishing composition includes a pH adjuster, and the pH adjuster is selected from an inorganic acid or an inorganic base.

8. The chemical mechanical polishing composition according to claim 7, It is characterized in that The pH regulator is HNO 3 or KOH.

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